In order to operate efficiently and effectively, internal combustion engines must have proper seals to prohibit the release of gases or liquids that may hinder an engines performance. In particular, sealing high pressure combustion gases within a cylinder is vital to efficient operation of an internal combustion engine, and in particular, a diesel engine. Proper seals between the cylinder liner and the cylinder head are essential for a diesel engine which relies on optimal pressure and temperature conditions for igniting fuel. If the cylinder liner and cylinder head are improperly sealed, then combustion gases could leak out of the cylinders during engine operation resulting in loss of power and engine efficiency. Different apparatus and methods have been developed in an attempt to provide an effective seal at the cylinder liner and cylinder head interface. One example of this attempt is found in U.S. Pat. No. 4,917,062 to Tapper et al. which discloses the use of a resilient polymeric "O"-ring compressed within complementary rectangular grooves in the cylinder head and the engine block when the cylinder head is tightened onto the cylinder block to effect a seal. The apparatus of Tapper et al., however, is not designed to effectively seal high pressure combustion gases in an internal combustion engine. For example, Tapper et al. employ a resilient polymeric "O"-ring that can break down due to high combustion gas pressures generated in the internal combustion engine.
A further combustion seal design is found in Russian Patent Application No. SU 1,481,451 A1 to Butov which discloses a seal for a joint between the cylinder head and cylinder liner of an internal combustion engine. The seal includes a seal ring formed of a deformable material and a cylinder head and cylinder liner having a series of concentric grooves formed therein. When the cylinder head is tightened, the ridges between each of the concentric grooves press into the seal ring to provide a seal between the cylinder head and the cylinder liner. The multiple grooves on both the cylinder head and cylinder liner add to the manufacturing costs of the sealing engagement due to the precision that is involved in ensuring that the respective grooves are properly mated.
German Patent Application No. 35 30 372 A1 to Heitjohann discloses a seal for a pressurized annular gap between two cylindrical surfaces. The seal includes a ring that is held in an annular groove provided in one of the two cylindrical surfaces. The reference refers to the ring as a "soft joint" which would imply that it is made from a soft material. As such, the structure disclosed in Heitjohann suffers from the same deficiencies as Topper et al. discussed above.
Another combustion seal design is found in U.S. Pat. No. 2,553,222 to Wallgren et al. which utilizes a packing ring that is compressed into a groove formed in a cylinder portion when the cylinder head is applied and secured. The packing ring comprises copper and is deformable within the cylinder groove. When the head is removed and subsequently reapplied, the packing ring may be reversed so that the ring is again pressed into the groove formed in the cylinder portion. The packing ring of Wallgren et al., however, provides only one point of seal between the cylinder head and cylinder portion, which increases the chance that high pressure combustion gases will escape from the cylinder during engine operation. As discussed above, this problem could be detrimental to engine performance and efficiency.
U.S. Pat. No. 5,275,139 to Rosenquist discloses a seal comprising a deep groove in the cylinder head and a complementary deep groove formed in the cylinder body. A loose fitting armor wrapped fire ring is positioned within the grooves of both the cylinder head and the cylinder body. The Rosenquist system is complex, in that, the seal requires a deep groove in the cylinder head as well as in the cylinder body resulting in increased manufacturing costs. In addition, the system does not use a cylinder liner, and thus, is not practical for many types of engines that use cylinder liners pressure fitted into a cylinder bore. The loose fitting armor wrap is also undesirable because it adds cost to the manufacturing process and has limited sealing capabilities.
Based on the limited teachings of the above-noted references there is a need for a combustion gas seal design that is simple to manufacture yet durable and effective in order to withstand extreme combustion gas pressure acting on the seal during engine operation. An improved seal increases engine efficiency to achieve maximum performance. Combustion seal designs that breakdown under high combustion gas pressure may result in undesirable downtime and costly repairs to the internal combustion engine. Therefore, it is imperative that a combustion seal is able to endure day-to-day engine operation and not breakdown under the high pressures and temperatures.